Process for the conversion of heavy residual oils



1959 M. D. ABBOTT ETAL 2,915,457

PROCESS FOR THE CONVERSION OF HEAVY RESIDUAL OILS Filed June 14, 1957 mm 3385 2.9: 92 mm 3x35 :93.

mm Om mohkmmzmumm INVENTORSI M. D. ABBOTT W. L. SNIDER e. E. LIEDHOLM Q35 64 QM Ill v HEIR ATTORNEY nited States 2,915,457 Patented Dec. 1, 1959 PROCESS FOR THE CONVERSION OF HEAVY RESIDUAL OILS Mortimer D. Abbott, Orinda, Warren L. Snider, Walnut Creek, and George E. Liedholm, Berkeley, Caiitl, assignors to Shell Development Company, New York, N.Y., a corporation of Delaware I Application June 14, 1957, Serial No. 665,820

4 Claims. (Cl. 208-74) This invention relates to an improved process for producing high grade gasolines from heavy hydrocarbon oils, e.g., straight run residues and vacuum flasher pitches.

It has been known for some time that larger quantities of high octane gasoline may be obtained from various heavy hydrocarbon oils by catalytic cracking than by any purely thermal treatment. 'However, not all hydrocarbon oils boiling above the gasoline range are suitable for catalytic cracking. For example, oils which have too large a percentage of refractory components such as polycyclic aromatics are difficult to crack and cause excessive amounts of coke to form on the catalyst particles. Moreover, various metal contaminants present in some hydrocarbon oils act to poison or inactivate the catalyst and must be drastically reduced prior to subjection such oils to the catalytic cracking treatment.

It has been proposed to obtain suitable quantities of catalytic crackingfeed stock from various hydrocarbon oils by subjecting them to a mild thermal cracking treatment with subsequent multi-stage separation. In this type of operation, the residual oil is first heated to a temperature which is only high enough to mildly crack certain of the heavier components of the oil, e.g., in a treatment sometimes referred toas visbreaking.. The gas, gasoline and gas oil distillates are separated from the thermally treated oil in a first stage separator at atmospheric pressure or greater, e.g., up to 100 p.s.i.g. The bottoms from the first stage separator are then sent to a second stage separator wherein the material is further separated into gas oil distillates and a pitchy residue at subatmospheric pressure, e.g., below 200 mm. of mercury. Each of the separators may contain a cyclone section wherein the vapors are separated from the entrained liquid and a tray section wherein the vapors are partially condensed into various fractions. The gas oil distillates from both separators contain a substantially smaller amount of metal contaminants than the original heavy residual oil which is an advantage in catalytic cracking. Variations of this type of operation are described for example in US. Patents 2,662,845 and 2,748,061 and are known in the art as two stage flash cracking processes.

In the catalytic cracking of oils boiling above the gasoline range, it has been proposed to carry out the process by first subjecting the oils to contact with the catalyst at a comparatively high temperature for a short period of time, e.g., 1-5 seconds, separating the gas and gasoline from the resulting cracked product and then subjecting the remaining oil to further contact with the catalyst in a second stage cracking zone at a low temperature for a longer period of time. The first stage of a process of this type is carried out by sending the vaporized feed stock and the catalyst up to a reactor having a large length to diameter ratio, i.e., a riser at a velocity greater than that which would cause an appreciable amount of backfiow of catalyst particles or the formation of a dense bed of such particles in the reactor. The cracked prodnet is separated from the catalyst at the top of the reactor and is partially condensed in a first stage fractionator with the gas and gasoline fraction being drawn off and at least part of the condensed cracked gas oil fraction being sent to the second stage reactor together with the catalyst from the first stage. The second stage of the process comprises a conventional reactor wherein the feed is contacted with a dense bed of catalyst at a temperature of about 800900 F. The catalyst is drawn off from the bottom of the second stage reactor and is transferred to a regenerator wherein the carbonaceous deposits are burned off with an oxygen containing gas. The catalyst is then recirculated to the first stage reactor and the product of the second stage is fractionated to separate the gasoline and second stage catalytically cracked gas oil fractions. A heavy catalytically cracked gas oil may be recycled to the second stage reactor. The catalyst used in this type of two stage process may be a conventional cracking catalyst, e.g., a synthetic catalyst such as silica combined with alumina, magnesia or zirconia or a natural catalyst made from a bentonite clay such as montmorillonite and other natural aluminum silicates such as kaolin and halloysite. An example of a two stage catalytic cracking process of the type described is shown for example in the Petroleum Refiner, vol. 35, No. 5, pages 166-170 (May 1956).

In combining a two-stage flash cracking process with a two-stage catalytic cracking process as described above, various problems must be overcome. For example, the gasoline obtained from the first stage fractionator of the flash cracking process is of relatively low octane number and must be upgraded for present day consumption, e.g.,

, by platforming which is a catalytic reforming process utilizing a supported platinum catalyst. However, the flash cracked gasoline usually contains a large quantity of sulfur which may exert a serious poisoning effect on the platinum so that it must be removed prior to platforming. Moreover, such gasolines also contain a large percentage of olefins which may have the eifect of overheating the platinum catalyst due to the exothermic nature of their hydrogenation during the platforming process; Thus,'it is advisable to pretreat the flash cracked gasoline'prior to platforming to eliminate olefins and sulfur.

In the two-stage catalytic cracking process, the feed to the second stage reactor contains a greater proportion of poly aromatics and other refractory components than the original catalytic cracking feed stock. This material is thus considerably more diflicult to crack and causes a greater degree of coke formation on the catalyst than the feed to the first stage reactor. Moreover, large quantities of catalytically cracked gas oils are produced in the second stage reactor which are more refractory and difficult to crack than either the first or second stage feed. As would be expected, this material has a much lower value than an equivalent quantity of gasoline. Under these circumstances, any process which has the effect of lowering the quantity of coke formation in the second stage reactor and of causing more gasoline to be formed at the expense of the second stage catalytically cracked gas oil is much to be desired.

It is an object of this invention to provide an integrated combination process of two-stage flash cracking and twostage catalytic cracking whereby a greater proportion of gasoline is obtained from heavy hydrocarbon oils such as straight run residues than is usually obtained from conventional processes. It is a further object of this invention to combine a two-stage flash cracking process and a two-stage catalytic cracking process with a separate hydrogenation step in such a manner that the gasoline produced in the flash cracking zone is entirely suitable as a' feedstock for a catalytic reforming process utilizing a catalyst which is sensitive to sulfur, the rate of coke formed on the cracking catalyst is decreased, and the amount of gasoline produced by the catalytic cracking process is increased at the expense of the catalytically cracked gas oil usually produced.

These objects are carried out by subjecting the gasoline from the first stage of the flash cracking process together with the gas oil from the first stage of the catalytic cracking process to catalytic hydrogenation, separating gasoline and gas oil fractions from the hydrogenated material, withdrawing the gasoline which is suitable for platforming, transferring the hydrogenated gas oil to the second stage catalytic cracking reactor, and separating gasoline and catalytically cracked gas oil fractions from the second stage product. Part of the heavy catalytically cracked gas oil may be recycled to the second stage catalytic cracking reactor or the hydrogenation reactor.

The invention will now be described in greater detail with reference to the drawing which is a highly schematic diagram of a process carried out in accordance with this invention.

The residual oil feed stock from line 1 enters the furnace 2 wherein it is subjected to a mild thermal treatment, e.g., at a temperature of 700-900 F. and a pressure of -300 p.s.i.g. for a period of 1-3 minutes. The thermally treated and vaporized material passes by line 3 to the first stage separator 5 wherein it is separated at a pressure of from 1 atmosphere absolute to 100 p.s.i.g. into a gas and gasoline fraction drawn off by line 6, a first stage light gas oil which is transferred to catalytic cracking by line 7, a first stage heavy gas oil drawn off by line 8, and heavy first stage bottoms which are transferred by line to the second stage separator. Part of the first stage heavy gas oil is recycled for reflux by line 12 and part is transferred to catalytic cracking by line 13. The gas and gasoline vapors are separated by the dephlegmator 15 into a flash cracked gasoline transferred to the hydrogenation unit by line 16 and gas drawn off by line 17. Thefirst stage bottoms are separated in the second stage vacuum separator 19 at a pressure of 5-200 mm. mercury absolute into a gas oil vapors which are drawn off by line 20, an extra heavy gas oil drawn off by line 21 and recycled to the furnace, and a pitchy residue drawn off by line 22 and sent to fuel oil blending. The gas oil vapors are separated in condenser 23 into a second stage light gas oil vapors transferred to catalytic cracking by line 24 and a condensed second stage heavy gas oil, part of which is recycled to the second stage separator as reflux by line 25 and part of which is sent to catalytic cracking by line 27.

The combined flash cracked distillate is transferred by line 24 to heater 28 wherein it is preheated to a temperature just below that at which substantial thermal cracking takes place, e.g., 700800 F. The preheated feed enters the first stage catalytic cracking reactor 29 which has a relatively large length to diameter ratio and is sent up through the reactor with regenerated cata lyst, the latter having been heated in the regenerator to a temperature sufficient to bring the feed up to reaction temperature, e.g., 950-1050 F. The superficial linear velocity of the materials in the reactor is high enough to prevent a dense bed of catalysts from forming, e.g., at least 30 feet per second. At this rate, there is reducedbacldiow of the catalyst particles which move almost as fast as the reactant and product vapors in what is known in the art as a disperse phase. After remaining in the first stage reactor for a relatively short period of time, e.g., 1-5 seconds, the catalyst and cracked product enter separator 30 which is made up of cyclones and baffles necessary to separate substantially all of the catalyst from the product vapors. The latter are transferred to first stage fractionator 31 wherein they are separated into a gas and gasoline faction drawn off by line 32, a gas oil fraction which is sent to the hydrogenation unit by line 33 and a resinous bottoms material drawn off by line 34. The catalyst is withdrawn from separator 30 by line 35 and enters the second stage catalytic cracking reactor with the second stage feed which is transferred to the reactor from the hydrogenation zone by line 37. The vapors in the second stage reactor move at a superficial linear velocity such that a conventional dense bed of catalyst particles form. The product vapors withdrawn from the reactor are transferred to the second stage fractionator 40 wherein they are separated into a gas and gasoline fraction withdrawn by line 41, a light catalytically cracked gas oil drawn off by line 42, a heavy catalytically cracked gas oil drawn off by line 43 and a slurry oil drawn off by line 45. Part of the heavy catalytically cracked gas oil and the slurry oil may be recycled to the second stage catalytic cracking reactor by lines 46 and 47, respectively. Alternatively, all or part of this material may be hydrogenated with the first stage catalytically cracked gas oil. The catalyst particles are transferred from the second stage reactor by line 49 to the regenerator 50 together with a combustion-supporting oxygen-containing gas which enters the regenerator by line 51. The

materials enter the regenerator at a rate such that a dense bed of catalyst particles form. The carbonaceous deposits are substantially burned ofi the catalyst particles which are thus heated to a temperature, e.g., 1050-1200 F., suflicient to bring the first stage catalytic cracking feed up to the reaction temperature. The catalyst is withdrawn from the regenerator by line 52 and is recycled to the first stage catalytic cracking reactor. The combustion gases formed in the regenerator are drawn off by line 53.

The first stage catalytically cracked gas oil from line 33 is preheated for hydrogenation in heater 58. The preheated hydrogenation feed by line 55 and fresh hydrogen by line 56 enter the hydrogenation reactor 57 where they are hydrogenated over the desired hydrogen uptake, e.g., in the range of -700 s.c.f./bbl. Also entering the hydrogenation reactor is the flash cracked gasoline from line 16 which is split up in manifold 54 into several streams entering the reactor at different points; the ease of evaporation of this material allows it to serve as an excellent cooling medium which prevents the exothermic heat of reaction from excessively raising the temperature. Either the total gas oil or only the heavy gas oil from the first stage catalytic cracking reactor may be hydrogenated. The material to be hydrogenated is contacted with a suitable hydrogenation catalyst which is active in the presence of sulfur at a suitable pressure and temperature. Catalysts which may be used are mixtures of cobalt and/or nickel oxide and molybdenum oxide supported on alumina, and a mixture of tungsten and nickel sulfides. The hydrogenation reaction may take place, for example, using a pressure of 750-2000-p.s.i.g., a temperature of 650-750 F., a recycled gas rate of 200-1200 s.c.f./bbl. and LHSV of 1-3. The hydrogen consumption may be varied depending on the feed composition. The hydrogenated and desulfurized product is separated in the reactor into lighter and heavier streams which are drawn ofi. by lines 59 and 60, respectively. The streams are further conventionally separated in dephlegmators 61, 62 and 63 and flasher 65 into a hydrogen-rich gas recycled to the reactorbyline 66, ahydrocarbon gas drawn off by line EXAMPLE A combination feed stock consisting of 53,417 pounds per hour of straight run residue which is 53.5% by weight of a West Texas crude oil, 267,745 pounds per hour of a straight run residue which is 30.13% by weight of the crude oil and 179,846 pounds per hour of a vacuum flasher pitch which is 18.5% by weight of the crude oil, is flash cracked in two stages as described above. The feed enters the furnace at a temperature of 600 F. and a pressure of 350 p.s.i.g. and is further heated to 860 P. which is sufiicient to vaporize the feed and mildly thermally crack various of its heavier components. The effluent from the furnace enters the first stage pressure separator wherein it is flashed at 40 p.s.i.g. The gas and gasoline and the first stage light and heavy gas oil distillates are drawn 01f, with part of the heavy gas oil recycled to the separator for reflux. The first stage bottoms are transferred to the second stage pressure separator wherein they are flashed at a temperature of 806 F. and a pressure of 20 mm. mercury absolute to separate second stage light and heavy gas oil distillates, an extra heavy gas oil which is recycled to the furnace and a pitchy residue. Part of the heavy gas oil is recycled to the second stage separator as reflux. A summary of the products from the flash cracking zone is given in Table I.

Table I .F lash cracking product summary The total flash cracked gas oil distillates which are at a temperature of 541 F. on leaving the flash cracking zone are reheated to a temperature of 750 F. and are transferred to the first stage catalytic cracking reactor wherein they are cracked with a synthetic silica-alumina catalyst to 50% conversion at a temperature of 1000 F. while in the reactor for about 1-3 seconds. The heavy catalytically cracked gas oil from the first stage fractionator is transferred to the hydrogenation reactor wherein it is hydrogenated with a catalyst comprising a mixture of nickel and molybdenum oxides supported on A2" extruded alumina pellets at a temperature of 705 F., a pressure of 750 p.s.i.g., a hydrogen to oil ratio of 1400 standard cubic feetper barrel. The hydrogenated material is separated into gas, a combination of hydrogenated flash cracked gasoline and hydrogasoline and a hydrogenated gas oil, the latter being transferred to the second stage catalytic cracking reactor. A comparison of the feed to the hydrogenation reactor and the product resulting from such hydrogenation is given in Table II excluding the flash cracked gasoline which is assumed to remain approximately the same in quantity before and after hydrogenation.

Table II Feed Product LHSV 1.0 Gravity, API 21. 5

H2 Uptake c.f./b 500 Sulfur Removal, percent w 94 Nitrogen Removal, percent 29 Polyaromatics Reduction 34 Analyses:

Sulfur, percent w 1.52 0.09 Nitrogen, percent w 0.07 O. 05 Basic Nitrogen, percent 0.025 0.0002 Molecular Weight 305 Hydrogasoline to 400 F O 2. 5

The hydrogenated gas oil is then transferred to the second stage catalytic cracking reactor wherein it is further cracked at a temperature of 850-900" F. in contact with the catalyst from the first stage reactor. The quantities in barrels per day of the various catalytically cracked and hydrogenated streams are shown in Table III.

Table III Barrels per day First stage catalytic cracking:

Flash cracked distillate feed 23,250

We claim as our invention:

1. A process of treating a residual oil so as to obtain maximum quantities of high grade gasoline which cornprises subjecting said oil to a mild thermal cracking treatment, separating said thermally treated oil in a first stage flashing zone at a pressure of 1 atmosphere absolute to p.s.i.g. into a gasoline fraction, gas oil distillates and heavy first stage bottoms, separating said first stage bottoms in a second stage flashing zone at a pressure of 5-200 mm. mercury absolute into gas oil distillates and a pitchy residue, sending the gas oil distillates from the first and second stageflashing zones up through a first stage catalytic carcking zone having a large length to diameter ratio wherein they are contacted with a cracking catalyst for 1-5 seconds at a temperature of 950-1050 F., the catalyst in said first stage catalytic cracking zone travelling upwards at a velocity suflicient to prevent appreciable backflow of catalyst particles, separating the catalyst from the first stage catalytically cracked products, separating the latter products into gas, gasoline and gas oil fractions, catalytically hydrogenating at least part of the first stage catalytically cracked gas oil together with the gasoline from said first stage flashing zone with a sulfur resistant hydrogenation catalyst to a hydrogen uptake of from about 100 to about 700 s.c.f./bbl., separating the hydrogenated. products into gasoline and gas oil fractions, transferring the hydrogenated gas oil and the catalyst from the first stage catalytic cracking zone to a second stage catalytic cracking zone wherein a dense bed of catalyst particles is formed and the hydrogenated gas oil is further catalytically cracked at a temperature of 800-900 F., withdrawing the products from the second stage catalytic cracking zone and-separating them into gas, gasoline. and gas oil fractions, transferring the catalyst from the second stage catalytic cracking zone together with a combustion supporting oxygen-containing gas to a regeneration zone, burning the carbonaceous deposits from the catalyst particles and transferring the hot regenerated catalyst back to the first stage catalytic cracking zone.

2. A processof treating a residual oil so as to obtain maximum quantities of high grade gasoline which corn,- prises subjecting said oil to a mild thermal cracking treatment, separating said thermally treated oil in a first stage flashing zone at a pressure of 1 atmosphere absolute to 100 p.s.i.g. into a gasoline fraction, gas oil distillates and heavy first stage bottoms, separating said first stage bottoms in a second stage flashing zone at a pressure of 5-200 mm. mercury absolute into gas oil distillates and a pitchy residue, sending the gas oil distillates from the first and second stage flashing zones up through a first stage catalytic cracking zone having a large length to diameter ratio wherein they are contacted with a cracking catalyst for 1-5 seconds at a temperature of 950- 1050 F., the catalyst in said first stage catalytic cracking zone travelling upwards at a velocity sufficient to prevent appreciable backflow of catalyst particles, separating the catalyst from the first stage catalytically cracked products, separating the latter products into gas, gasoline and gas oil fractions, catalytically hydrogenating at least part of the first stage catalytically cracked gas oil together with the gasoline from said first stage flashing zone at a temperature of 650750 F., a pressure of 7502000 p.s.i.g., a recycle gas rate of 200-1200 s.c.f./bbl. and a liquid hourly space velocity of 1-3, separating the hydrogenated products into gasoline and gas oil fractions, transferring the hydrogenated gas oil and the catalyst from the first stage catalytic cracking zone to a second stage catalytic cracking zone wherein a dense bed of catalyst particles is formed and the hydrogenated gas oil is further catalytically cracked at a temperature of 800-900 F., withdrawing the products from the second stage catalytic cracking zone and separating them into gas, gasoline and gas oil fractions, transferring the catalyst from the second stage catalytic cracking zone together with a combustion supporting oxygen-containing gas to a regeneration zone, burningthe carbonaceous deposits from the catalyst particles and transferring the hot regenerated catalyst back to the first stage catalytic cracking zone.

3. A process of treating a residual oil so as to obtain maximum quantities of high grade gasoline which comprises subjecting said oil to a mild thermal cracking treatment, separating said thermally treated oil in a first stage flashing zone at a pressure of 1 atmosphere absolute to 100 p.s.i.g. into a gasoline fraction, gas oil distillates and heavy first stage bottoms, separating s'aid first stage bottoms in a second stage flashing zone at a pressure of 5-200 mm. mercury absolute into gas oil distillates and a pitchy residue, sending the gas oil distillates from the first and second stage flashing zones up through a first stage catalytic cracking zone having a large length to diameter ratio wherein they are contacted with a cracking catalyst for 1-5 seconds at a temperature of 950-1050" E, the catalyst in said first stage catalytic cracking zone travelling upwards at a velocity sufficient to prevent appreciable backflow of catalyst particles, separating the catalyst from the first stage catalytically cracked products, separating the latter products into gas, gasoline, light gas oil and heavy gas oil fractions, catalytically hydrogenating the heavy gas oil fraction from the first stage catalytic cracking zone together with the gasoline from the said first stage flashing zone, separating the hydrogenated products into gasoline and gas oil fractions, transferring the hydrogenated gas oil and the catalyst from the first stage catalytic cracking zone to a second stage catalytic cracking zone wherein a dense bed of catalyst par-ticles is formed and the hydrogenated gas oil is further catalytically cracked at a temperature of 800900 F., Withdrawing the products from the second stage catalytic cracking zone and separating them into gas, gasoline and gas oil fractions, transferring the catalyst from the second stage catalytic cracking zone together with a combustion supporting oxygentontaining gas to a regeneration zone, burning the carbonaceous deposits from the catalyst particles and transferring the hot regenerated catalyst back to the first stage catalytic cracking zone.

4. A process of treating a residual oil so as to obtain maximum quantities of high grade gasoline which comprises subjecting said oil to a mild thermal cracking treatment, separating said thermally treated oil in a first stage flashing zone at a pressure of 1 atmosphere absolute to p.s.i.-g. into a gasoline fraction, gas oil distillates and heavy first stage bottoms, separating said first stage bottoms in a second stage flashing zone at a pressure of 5-200 mm. mercury absolute into gas oil distillates and a pitchy residue, sending the gas oil distillates from the first and second stage flashing zones up through a first stage catalytic cracking zone having a large length to diameter ration wherein they are contacted with a cracking catalyst for 1-5 seconds at a temperature of 950- 1050 F., the catalyst in said first stage catalytic cracking zone travelling upward at a velocity suflicient to prevent appreciable backfiow of catalyst particles, separating the catalyst from the first stage catalytically cracked products, separating the latter products into gas, gasoline and gas oil fractions, catalytically hydrogenating at least part of the first stage catalytically cracked gas oil together with the gasoline from said first stage flashing zone and at least part of the second stage catalytically cracked gas oil hereinafter specified, separating the hydrogenated products into gasoline and gas oil fractions, transferring flae hydrogenated gas oil and the catalyst from the first stage catalytic cracking zone to'a second stage catalytic cracking zone wherein a dense bed of catalyst particles is formed and the hydrogenated gas oil is further catalytically cracked at a temperature of 800900 F., withdrawing the products from the second stage catalytic cracking zone and separating them into gas, gasoline and second stage catalytically cracked gas oil fractions, transferring the catalyst from the second stage catalytic cracking zone together with a combustion supporting oxygencontaining gas to a regeneration zone, burning the carbonaceous deposits from the catalyst particles and transferring the hot regenerated catalyst back to the first stage catalytic cracking zone.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PROCESS OF TREATING A RESIDUAL OIL SO AS TO OBTAIN MAXIMUM QUANTITIES OF HIGH GRADE GASOLINE WHICH COMPRISES SUBJECTING SAID OIL TO A MILD THERMAL CRACKING TREATMENT, SEPARATING SAID THERMALLY TREATED OIL IN A FIRST STAGE FLSHING ZONE AT A PRESSURE OF 1 ATMOSPHERE ABSOLUTE TO 100 P.S.I.G. INTO A GASOLINE FRACTION, GAS OIL DISTILLATES AND HEAVY FIRST STAGE BOTTOMS, SEPARATING SAID FIRST STAGE BOTTOMS IN A SECOND STAGE FLASHING ZONE AT A PRESSURE OF 5-200M MM. MERCURY ABSOLUTE INTO GAS OIL DISTILLATES AND A PITCHY RESIDUE, SENDING THE GAS OIL DISTILLATES AND A CATALYTIC CARCKING ZONE HAVING A LARGE LENGTH TO DIAMETER RATIO WHEREIN THEY ARE CONTACTED WITH A CRACKING CATLYST FOR 1-5 SECONDSF AT A TEMPERATURE OF 950-1050*F., THE UPWARDS AT A VELOCITY SUFFICIENT TO PREVENT APPRECIABLE BACKFLOW OF CATALYST PARTICLES, SEPARATING THE CATALYST FROM THE FIRST STAGE CATALYTICALLY CRACKED PRODUCTS, SEPARATING THE LATTER PRODUCTS INTO GAS, GASOLINE AND GAS OIL FRACTIONS, CATALYTICALLY HYDROGENATING AT LEAST PART OF THE FIRST STAGE CATALYSTICLLY CRACKED GAS OIL TOGETHER WITH THE GASOLINE FROM SAID FIRST STAGE FLASHING ZONE WITH A SULFUR RESISTANT HYDROGENATION CATALYST TO A HYDROGEN UPTAKE OF FROM ABOUT 100 TO ABOUT 700 S.C.F./BBL., SEPARATING THE HYDROGENATED PRODUCTS INTO GASOLINE AND GAS OIL FRACTIONS, TRANSFERRING THE HYDROGENATED GAS OIL AND THE CATLYST FROM 